CompuServe Messages

Bradley: You've covered most of it. First, they have to handle the Xon/Xoff. Next, they've got to handle the time slicing, and provide for some fine tuing in that area. If you want the spooler to work with AutoCAD's AutoSpool feature they have to be able to watch for when DOS closes a file and then check to see if it's an AutoCAD plot file in the spooler directory. In order for the spooler to work efficiently it needs to have an internal buffer so it always has data ready to pump out through the port once it gets an Xon and once it's time slice comes along. And it works best when it's interrupt driven which means it's got to work properly with the serial port's UART chip. It needs to be adjustable for the baud rate and communications protocols that the plotter and/or CAD program expect to use. So basically, the DOS print command is poorly suited for this task because: 1. it requires a different cable than AutoCAD's standard because PRINT can't do Xon/Xoff. 2. PRINT doesn't let you adjust the time slice 3. PRINT isn't interrupt driven 4. PRINT can't queue automatically There are other things a good spooler does as well, like queue management and plot logs and things like that. David